Fuel system

ABSTRACT

A dual liquid fuel system for an internal combustion gasoline engine. The system delivers a volatile fuel to the carburetor or other fuel metering system on start-up and until the engine attains an operating temperature that does not normally require choking when using a normal gasoline. The system then switches fuels and delivers normal gasoline. The system includes means to partially vaporize gasoline and condense the vapor to obtain the volatile fuel used in start and warm-up.

United States Patent [1 1 Hirschler, Jr. et al.

[ Apr. 30, 1974 FUEL SYSTEM Inventors: Daniel A. Hirschler, Jr,

Birmingham; Frederick J. Marsee, Clawson, both of Mich.

Assignee: Ethyl Corporation, Richmond, Va.

Filed: Aug. 23, 1971 Appl. No.: 174,015

Related US. Application Data Continuation-impart of Ser. No. 152,678, June 14, 1971.

US. Cl. 123/127, 123/122 E, 123/133, 123/179 G, 123/136 Int. Cl. F02m 13/00 Field of Search 123/127, 133, 179 G, 134, 123/2, 3,180 R, 180 A, 180 P, 180 AC; 196/9 8, 104; 208/356, 359, 361, 366

References Cited UNITED STATES PATENTS Woolson... 123/127 1,744,953 1/1930 Dienner 123/127 2,098,575 11/1937 Flamini 123/127 3,021,681 2/1962 Perry 123/133 1,477,860 12/1923 Adams 196/98 1,576,766 3/1926 Kloepper 123/127 Primary ExaminerLaurence M. Goodridge Attorney, Agent, or Firm-Donald L. Johnson; Robert -A. Linn; Joseph D Odenweller ABSTRACT A dual liquid fuel system for an internal combustion gasoline engine. The system delivers a volatile fuel to the carburetor or other fuel metering system on startup and until the engine attains an operating temperature that does not normally require choking when 4 using a normal gasoline. The system then switches fuels and delivers normal gasoline. The system includes means to partially vaporize gasoline and condense the vapor toobtain the volatile fuel used in start and warm-up.

18 Claims, 10 Drawing Figures PATENTEDAPRIm um SHEET 1 8F 5 FIGURE I VOLATILE FUEL INTERLOCKED SOLENOID ACTUATED FIGURE 2 FATENTEM'R 30 I974 SHEET 2 BF DGASOLINE FIGURE 4 VENT CONDUIT q.- 53 V CP P 56 FROM VOLATILE REG A 52\ FUEL T NK TO VOLATILE FUEL TANK FIGURE 5 TO CARBURETOR 59 FUEL BOWL TO CARBURETOR P'A'TENTEDAPR so 1914 3,807,3 1?

SHEET 3 BF 5 VENT CONDUlT Q 64 CP 5 66 FROM VOLATILE TO VOLATILE FUEL TANK TO CARB'URETOR w FUEL BOWL FIGURE 6 79 HOT LIQUID FROM ENGINE FIGURE 7 PATENTEDAPRw m4 330K377 sum s or 5 FIGURE IO FUEL SYSTEM This application is a Continuation-in-Part of application Ser. No. l52,678,'filed June 14, l97l.

BACKGROUND The exhaust gas of internal combustion engines contains various amounts of unburned hydrocarbons, carbon monoxide, and nitrogen oxides (NO Emission of these materials to the atmosphere is undesirable. The problem is more acute in urban areas having a high concentration of motor vehicles.

During recent years, researchers have investigated extensively means of reducing exhuast emission. This research has been quite fruitful. As a result, presentday automobiles emit but a fraction of undesirable materials compared to those of less than a decade ago. These improved results have come about through such means as improved carburetion, ignition timing modification, exhaust recycle, exhaust manifold air injection, use of lean air/fuel ratios, positive crankcase ventilation, and the like.

Despite the tremendous advances that have been made, further improvements are desirable. Federal standards by I975 are expected to require reduction of emissions to only about 10 percent of the level of 1970. A major obstacle in achieving further reduction in exhaust emissions is the fact that the engine requires a richer air/fuel mixture during start and warm-up. During this period exhaust emissions of even the lowest emitting engine is appreciably increased. In the case of carburetor induction engines the required richer'air/fuel mixture is usually attained by placing a choke valve in the air passage above the carburetor venturi, which serves to restrict airflow. In most, but not all, gasolinepowered vehicles the choke is automatically controlled by engine temperature. As soon as the engine reaches an adequate operating temperature (i.e. a temperature at which it can operate smoothly without choking) the choke opens. In normal operation this takes about 2-3 minutes.

In the past, attempts have been made to eliminate the need for this rich operating warm-up period by operating the engine on liquid petroleum gas (LPG) during the warm-up period and switching to gasoline after operating temperature is attained. A drawback of this system is that it requires the vehicle operator to obtain two different kinds of fuel-gasoline and LPG.

An object of the present invention is to provide a fuel induction system that results in lower exhaust emissions. A further object is to provide a fuel induction system that allows an engine to start and warm-up without the necessity of operating the engine at a rich air/fuel ratio. A still further object of the invention is to provide a dual liquid fuel system with self-generation of the more volatile liquid fuel from the normal gasoline fuel, thus eliminating the necessity of the vehicle operator obtaining two separate fuels. Another object is to provide a method of operating a gasoline engine in a manner that will result in reduced exhaust emissions.

SUMMARY The above and other objects are accomplished by providing a dual liquid fuel system that will operate using a single liquid fuel metering means. The system includes means for delivering both a high volatility liquid fuel and normal gasoline to the engine fuel metering systemeither carburetted or fuel injected. Volatile fuel is delivered during start and warm-up and normal gasoline is delivered when the engine attains an operating temperature that allows smooth operation with normal gasoline at the lean air/fuel ratios normally employed for warmed-up operation. Another way of viewing this is that the fuel system allows start and warm-up of the engine without carburetor choking.

The system includes means for draining residual gasoline from the fuel metering system when the engine is turned off. In addition, the system includes means for generating its own supply of volatile fuel by partially vaporizing normal gasoline and condensing the vapors.

A further object is to provide a dual fuel system that feeds gasoline and gaseous fuel to the engine during selected periods of operation. The gaseous fuel is obtained from the gasoline, thus circumventing the need to fuel the vehicle with two separate fuels.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic of the basic dual liquid fuel system showing a reservoir for both volatile fuel and normal gasoline and conduits for delivering either through a switching valve to the fuel bowl of the carburetor. Also shown is a carburetor drain conduit having a valve which allows the carburetor to drain when the engine is turned ofi.

FIG. 2 is a cross-section of a carburetor having separate fuel bowls for the normal gasoline and the volatile fuel and interlocked valves for switching from one fuel to the other. The drawing shows the valve functioning to permit delivery of the fuel from the volatile fuel bowl such as would occur during start and warm-up.

FIG. 3 is a schematic of the dual liquid fuel system showing itsconnection to a carburetor on an internal combustion gasoline engine. Also shown is an automatic fuel vaporizer and finned tube condensing system for self-generation of the volatile fuel supply. The drawing also shows liquid level controls in the vaporizer and in'the volatile fuel container which function to actuate pumps which control the liquid level in the vaporizer and volatile fuel container. Also shown are valves in the two fuel delivery conduits for switching from one fuel to the other. Also included is a valved drain line from the carburetor to the normal gasoline tank permitting drain of residual fuel when the engine is turned off.

FIG. 4 is a schematic of the dual liquid fuel delivery system showing the vaporized fluid conduit wrapped around the vaporizing chamber in a heat exhange relationship such that the heat evolved on condensation of the vaporized light ends is transferred to the fuel undergoing partial vaporization.

FIG. 5 is a schematic of another embodiment of the dual liquid fuel delivery system showing the vaporizing chamber contained within the gasoline tank and in contact with the normal gasoline. The vapor conduit from the vaporizing chamber is also coiled within the gasoline tank in contact with the normal gasoline which serves to cool the vapor conduit and allow it to function as a condenser.

FIG. 6 is a schematic of the duel liquid fuel delivery system showing the fuel vaporizer separate from the gasoline tank and having the vapor conduit coiled within the vaporizing chamber thereby transferring heat of condensation to the fuel undergoing vaporization.

FIG. 7 is a schematic of the dual liquid fuel delivery system in which the fuel vaporizer is jacketed and hot liquid from the engine cooling system is circulated in the jacket to assist vaporization. A finned-tube condensing system is shown.

FIG. 8 is a schematic of the dual liquid fuel delivery system including a gasoline tank, vaporizing chamber, condenser, volatile fuel storage tank and volatiledepleted fuel storage tank connected to the gasoline conduit to permit feeding of the volatile-depleted fuel directly to the carburetor fuel bowl rather than returning it to the gasoline tank.

FIG. 9 is a schematic of a dual fuel system including a liquid fuel carburetor and a gaseous fuel metering device. The gaseous fuel is extracted from the normal gasoline in the vaporizer and stored in the volatile fuel tank from which it is fed during specified periods through pressure reduction valves and vaporizer to the gaseous fuel metering device.

FIG. 10 is a cross-section of a typical gaseous fuel metering device such as the one circled in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a preferred embodiment of the invention is a dual liquid fuel delivery system for a gasoline operated spark ignited internal combustion engine having a gasoline tank 1 for liquid hydrocarbon fuel of the gasoline boiling range (referred to hereafter as normal gasoline) and a container for liquid hydrocarbon fuel of the lower gasoline boiling range 2 (referred to hereafter as volatile fuel).

Liquid hydrocarbon fuels of the gasoline boiling range are mixtures of hydrocarbons having a boiling range of from about 80 to about 430F. as measured by ASTM method D-86. Of course, these mixtures can contain individual constituents boiling above or below these figures. These hydrocarbon mixtures contain aromatic hydrocarbons, saturated hydrocarbons and olefinic hydrocarbons. The bulk of the hydrocarbon mixture is obtained by refining crude petroleum by either straight distillation or through the use of one of the many known refining processes, such as thermal cracking, catalytic cracking, catalytic hydroforming, catalytic reforming, and the like. Generally, the final gasoline is a blend of stocks obtained from several refinery processes. The final blend may also contain hydrocarbons made by other procedures such as alkylate made by the reaction of C olefins and butanes using an acid catalyst, such as sulfuric acid or hydrofluoric acid.

Preferred gasolines are those having a Research Octane Number of at least 85. A more preferred Research Octane Number is 90 or greater. It is also preferred to blend the gasoline such that it has a content of aromatic hydrocarbons ranging from 10 to about 60 volume percent, an olefinic hydrocarbon content ranging from 0 to about volume percent, and a saturate hydrocarbon content ranging from about 40 to 80 volume percent, based on the whole gasoline.

In order to obtain fuels having properties required by modern automotive engines, a blending procedure is generally followed by selecting appropriate blending stocks and blending them in suitable proportions. The required octane level is most readily accomplished by employing aromatics (e.g., BTX, catalytic reformate,

or the like), alkylate (e. g., C saturates made by reacting C olefins with isobutane using a HF or H catalyst), or blends of different types.

The balance of the whole fuel may be made up of other components such as other saturates, olefins, or the like. The olefins are generally formed by using such procedures as thermal cracking, catalytic cracking and polymerization. Dehydrogenation of paraffins to olefins can supplement the gaseous olefins occurring in the refinery to produce feed material for either polymerization or alkylation processes. The saturated gasoline components comprise paraffins and naphthenes. These saturates are obtained from (I) virgin gasoline by distillation (straight run gasoline), (2) alkylation processes (alkylates) and (3) isomerization procedures (conversion of normal paraffins to branched-chain paraffins of greater octane quality). Saturated gasoline components also occur in so-called natural gasoline. In addition to the foregoing, thermally cracked stocks, catalytically cracked stocks and catalytic reformates contain saturated components.

Utilization of non-hydrocarbon blending stocks or components in formulating the fuels used in this invention is feasible and, in some instances, may actually be desirable. Thus, use may be made of methanol, tertiary butanol and other inexpensive, abundant and nondeleterious oxygen-containng fuel components.

The normal gasoline may contain any of the other additives normally employed to give fuels of improved quality, such as tetraalkyllead antiknocks including tetramethyllead, tetraethyllead, mixed tetraethyltetramethyllead, and the like. They may also contain antiknock quantities of other agents such as cyclopentadienyl nickel nitrosyl, methylcyclopentadienyl manganese tricarbonyl, and N-methyl aniline, and the like. Antiknock promoters such as tert-butyl acetate may be included. Halohydrocarbon scavengers such as ethylene dichloride, ethylene dibromide and dibromo butane may be adeed. Phosphorus-containing additives such as tricresyl phosphate, methyl diphenyl phosphate, diphenyl methyl phosphate, trimethyl phosphate, and tris(,B- chloropropyl)phosphate may be present. Antioxidants such as 2,6-di-tert-butylphcnol, 2,6-di-tert-butyl-pcresol, phenylenediamines such as N- isopropylphenylenediamine, and the like, may be present. Likewise, the gasoline can contain dyes, metal deactivators, or any of the additives recognized to serve some useful purpose in improving the gasoline quality.

The liquid hydrocarbon fuel of the lower gasoline boiling range, referred to as volatile fuel, are hydrocarbons having a final boiling point below that of normal gasoline. In the present invention it is not necessary to place an exact value on this final boiling point and, in fact, it can vary when the dual fuel system is used with different engines. The requirement is that the volatile fuel have a final boiling point low enough such that the particular engine to which the dual fuel system is connected will start and operate smoothly during warm-up without resorting to a richer air/fuel ratio than is required for operation at normal operating temperature. This is not to say that the use of a richer air/fuel ratio is excluded because under very cold conditions a slightly richer mixture may be required, especially to start the engine. This richer mixture is readily furnished by such means as choking the engine. However, the amount of time that the enriched air/fuel ratio is used will be substantially less than required without the dual 2 fuel system of this invention and, accordingly, even when some choking is required, the overall exhaust emissions will be still greatly reduced by the use of the dual fuel system of this invention.

The optimum final boiling point for the volatile fuel to be used in the dual fuel system on a particular engine is best determined experimentally taking into account the conditions such as temperature and humidity, etc., under which the engine will be operated. A useful boiling range for the volatile fuel is from about 60300F. Especially good results are obtained in most applications using a volatile fuel having a normal boiling range of from about 70-l50F. (ASTM D-86). The most preferred volatile fuel'is made up of the light ends (low boilers) obtained from normal gasoline. In fact, further embodiments of this invention, to be described in detail hereafter, include in the dual liquid fuel system means for removing the light ends from normal gasoline and using these as the volatile fuel during start and warm- Referring again to FIG. 1, the dual fuel system includes a liquid fuel conduit 3 connecting gasoline tank 1 through fuel selector valve 4 to fuel pump 5 which connects to fuel bowl 6 of carburetor 7. The carburetor shown is a single venturi type but the fuel system is equally applicable to multiple venturi carburetors such as those having 2, 3 or 4 venturi.

Volatile fuel tank 2 is connected by volatile liquid fuel conduit 8 to fuel selector valve 4 which connects through fuel pump 5 to fuel bowl 6 of carburetor 7. As shown in FIG. 1, fuel selector valve 4 is set to deliver normal gasoline from gasoline tank 1 to carburetor 7. By revolving the selector valve counter-clockwise, as shown by the arrow, fuel selector valve 4 will function to deliver volatile fuel from volatile fuel tank 2 to carburctor 7.

Fuel bowl 6 has a fuel drain 9 which can drain residual fuel from fuel bowl 6 through drain conduit 10 to gasoline tank 1. Drain valve 11 in drain conduit 10 is shown closed and is opened when it is desired to drain fuel bowl 6. I

In operation, the embodiment shown in FIG. 1 functions as follows. Starting with a cold engine, fuel selector valve 4 is set to open the flow path from volatile fuel tank 2 through fuel pump 5 to fuel bowl 6. Fuel selector valve 4 may be set manually, but is preferably positioned automatically in response to engine temperature. A temperature responsive bimetal switch can be used to signal valve actuating means to set fuel selector valve 4 to supply the proper fuel to fuel bowl 6 depend ing upon a predetermined engine temperature. The bimetal switch can be positioned to respond to engine temperature at any of several locations such as carburetor temperature, coolant temperature, oil tempera ture, or multiple bimetal switches can be used to respond to temperature at more than one location, thus requiring more than one location to attain a predetermined operating temperature before the circuit is completed to signal the valve actuating means to switch fuel selector valve 4 from one fuel to another. The predeterminedtemperature should be such that when the selector valve 4 is signalled to switch from delivering fuel from volatile fuel tank 2 to normal gasoline tank 1 the engine will operate smoothly with little, or preferably no, enrichment in the air/fuel ratio by means such as choking. This operating temperature need not be the final normal operating temperature of the engine but, rather, an intermediate temperature somewhere between the cold engine and the final operating tempera ture. The operating temperature at which selector valve 4 switches from volatile fuel to normal gasoline approximates the same temperature at which the wellknown automatic choking in a conventional fuel system would open because, in essence, the delivery of the volatile fuel replaces, or substantially replaces, the use of thechoke.

When the engine starter is engaged, fuel pump 5 fills fuel bowl 6 with volatile fuel. This is delivered through fuel nozzle 12 to carburetor venturi 13 where it is mixed with air and inducted into the engine. By the use of the present fuel system, nozzle 12 delivers fuel at a leaner air/fuel ratio than would otherwise be required to start the engine using normal gasoline. For example, the engine can be started at air/fuel ratios of about l3-l7:l whereas conventional systems require a much richer ratio. Under very adverse conditions, such as very low temperature, only minimal enrichment may be required to allow the engine to start and operate smoothly during warm-up.

When the engine reaches an operating temperature at which it can operate smoothly on normal gasoline with little or no choking, selector valve 4 is switched such that it closes the path from volatile fuel tank 2 and opens the path from normal gasoline tank 1 such that fuel bowl 6 is supplied with normal gasoline. As mentioned above, this can be accomplished manually but is preferably accomplished automatically in response to engine temperature.

After the engine has operated using normal gasoline and is turned off fuel bowl 6 will contain residual normal gasoline. Once the engine cools it will not start and run smoothly on this residual normal gasoline without some enrichment of the air/fuel ratio-in other words, some choking would be required. To avoid this, fuel bowl 6 is preferably drained after each use so that on the next start-up the initial fuel supplied to the carburetor will be volatile fuel. This is accomplished by opening drain valve 11 allowing the residual normal gasoline in fuel bowl 6 to drain through drain conduit 10 to normal gasoline tank 1. Optionally, the fuel bowl could drain to some other container provided for that purpose. Opening of drain valve 11 can be accomplished manually but preferably it is made automatic. One method of accomplishing this is to provide valve actuating means such as an electrical solenoid which keep valve 11 closed when the engine electrical engine system is turned on and open valve 11 when the ignition system is turned off. By this means when the engine is again started drain valve 11 will automatically close and either volatile fuel or normal gasoline will be delivered to fuel bowl 6 depending upon engine temperature.

Referring now to FIG. 2, another embodiment of the invention is shown in which a dual fuel bowl carburetor 20 is provided which has a fuel bowl for normal gasoline 21 and a separate fuel bowl for volatile fuel 22. Selection of fuel delivered to carburetor venturi 23 is accomplished by interlocked valves 24 and 25. The interlocking provides that when one valve is open the other is closed. As shown, valve 25 is open and volatile fuel is being delivered to venturi 23 which would be the proper selection at engine start-up and warm-up. When the engine attains operating temperature, valve 25 is closed and valve 24 opens such that normal gasoline is delivered to venturi 23.

Valves 24 and 25 can be operated manually but are preferably coupled with the previously-described engine temperature sensing bimetal switch which was used to actuate valve 4 in FIG. 1. In this manner, valve 25 will be automatically opened on start and warm-up.

When the engine attains smooth operating temperature, valve 25 will automatically close and valve 24 will open. Valves 24 and 25 are also interlocked with valve 26 in normal gasoline conduit 27 and valve 28 in volatile fuel conduit 29 such that when valve 25 is open valve 28 is open and valves 24 and 26 are closed. Likewise, when the engine attains operating temperature and valve 24 opens valve 26 also opens and valves 25 and 28 close.

In FIG. 2 each of fuel bowls 21 and 22 have individual fuel delivery passages. In a similar arrangement the carburetor can be modified such that only a single fuel delivery passage through a main nozzle is provided for each venturi. This single nozzle is supplied with fuel from either the volatile fuel bowl or the normal gasoline bowl as required and the selection of which fuel is delivered to the single nozzle is controlled by valves in the fuel passage connecting the individual fuel bowls to the common nozzle. These valves function in a manner similar to valves 24 and 25.

FIG. 3 shows the dual fuel system connected to an internal combustion engine having carburetor fuel metering means. The system includes an integral selfgeneration unit for obtaining volatile fuel from normal gasoline. Gasoline tank 30 is connected by liquid fuel conduit 31 to fuel inlet 32 of the carburetor. In fuel conduit 31 is fuel pump 33 and fuel selector valve 34. A second liquid fuel conduit connects gasoline tank 30 through one-way pressure regulating valve 36 to the top of vaporizing chamber 37 which is formed by a substantially cylindrical side wall and end closures. Vaporizing chamber 37 is connected to the inlet of vapor compressor 38 by vapor conduit 39 entering vaporizing chamber 37 through the top end closure. The outlet of compressor 38 is connected to the inlet of finned tube condenser 30A. The outlet of condenser 30A is connected by volatile fuel condensate conduit 31A through one'way check valve 32A to spherical volatile fuel tank 33A. The bottom of volatile fuel tank 33A is connected by volatile liquid fuel conduit 34A through fuel selector valve 35A to the fuel inlet 32 of the carburetor. Located in conduit 34A is pressure regulating valve 38B. The top of volatile fuel tank 33A is connected through pressure relief valve 36A by a second vapor conduit 37A back to gasoline tank 30.

Vapor chamber 37 connects through its bottom end closure to the inlet of volatile-depleted pump 38A. The outlet of pump 38A connects through volatile-depleted fuel conduit 39A to gasoline tank 30. Located in conduit 39A is one-way check valve 308.

Drain conduit 31B connects a drain outlet at the bottom of the carburetor fuel bowl such as drain 9 in FIG. 1 through valve 328 to fuel conduit 31.

Bimetal thermo switch 338 responds to engine coolant temperature and is connected by actuating means to valves 34 and 35A.

Located inside vaporizing chamber 37 is liquid level actuated switch 348 which connects through the side wall of chamber 37 by actuating means 36B to pump 38A.

Located inside volatile fuel tank 33A is liquid level actuated switch 353 which is connected by actuating means 378 to pump 38.

In operation, starting with a cold engine, turning the ignition on causes drain valve 32B to close. Thermo switch 338 responding to the low engine temperature has valve 35A in an open position and valve 34 in a closed position. Volatile fuel from volatile fuel tank 33A flows through conduit 34A and fills the fuel bowl of the carburetor. If required, an auxiliary fuel pump can be installed in conduit 34A. This is not usually required because the volatile fuel is under slight pressure which is regulated by pressure regulator valve 388 such that the volatile fuel at the carburetor can be controlled by a standard float actuated fuel bowl valve. Actuating the starter starts the engine which operates without choking using the volatile liquid fuel.

After 23 minutes of operation the liquid coolant temperature rises to a predetermined level at which experience has shown the particular engine can operate on normal gasoline without choking. Thermo switch 338 senses this temperature and actuates valve 35A to close and valve 34 to open. During continued operation normal gasoline is supplied to the carburetor from gasoline tank 30 through fuel conduit 31.

Assuming the liquid level in volatile fuel tank 33A has dropped below a predetermined level (this predetermined level should provide enough reserve volatile fuel to start and warm-up the engine), liquid level actuated switch 358 closes which starts pump 38. Pump 38 evacuates vaporizing chamber 37 pumping the residual vapor therein towards condenser 30A. When the pressure in chamber 37 drops to a predetermined level pressure regulating valve 36 opens and meters normal gasoline from gas tank 30 through conduit 35 into evacuated vaporizing chamber 37. The predetermined pressure differential which causes pressure regulating valve 36 to open is such that the light ends of the normal gasoline will vaporize. A useful pressure differential is that which will cause up to about 10-50 per cent of the normal gasoline to vaporize. The normal gasoline thus admitted to the vaporizing chamber is partially vaporized due to the reduced pressure. The vapors formed are pumped by pump 38 towards condenser 30A where they compress and liquefy releasing heat which is radiated by the finned-tube condenser 30A. The condensate so formed is pumped through one-way check valve 32A into volatile fuel tank 33A. If noncondensables are included in the condensate and cause the pressure in volatile fuel tank 33A to rise above about 5-75 psig, pressure relief valve 36A opens and vents the non-condensables back to gas tank 30 until the pressure in volatile fuel tank 33A drops to an acceptable level.

As fuel continues to be sucked into vaporizing chamber 37 the volatile-depleted portion of the fuel collects at the bottom of chamber 37. When the liquid level in chamber 37 reaches a predetermined level, liquid level actuated switch 34B closes causing pump 38A to operate which pumps the volatile-depleted fuel through volatile-depleted conduit 39A and one-way check valve 30B to gas tank 30.

When the liquid level in volatile fuel tank 33A rises to a satisfactory level switch 358 turns off pump 38. As soon as the liquid level in vaporizing chamber 37 drops below the predetermined level switch 348 shuts off pump 38A. At this stage the self-generation of volatile fuel is completed.

When the engine is stopped by turning off the ignition, drain valve 328 opens and drains the fuel bowl and valve 35A remains closed, or if open, closes to prevent volatile fuel from entering the fuel bowl while drain valve 328 is open. If the engine is restarted while still above operating temperature valve 323 will close, and since thermo switch 338 is still sensing adequate operating temperature, valve 35A will remain closed and valve 34 will be open. Hence, the carburetor will be supplied with normal gasoline. However, if the engine remains off long enough to lower the engine temperature below operating temperature, then valve 35A will open and valve 34 will be closed and the sequence will be as described above for starting a cold engine.

It is desirable to include in the vehicle an override system which cuts out the automatic fuel switch control by engine temperature. This is to handle the situation in which the engine is cold and thermo switch 33B is signaling valve 35A to open and deliver volatile fuel to the carburetor bowl during a period when the volatile fuel supply in tank 33A has been depleted. In this event, the automatic system is cut-out and normal gasoline is delivered to the carburetor and the engine started in the conventional manner using a choke.

In another aspect of the invention it may be desirable to control the ratio between the pumping volumes of FIGS. 4-6 show embodiments of the invention similar to that of FIG. 3 except that the volatile fuel selfgeneration system is modified to provide heat exchange from the condenser to the vaporizer. Partial vaporization of the normal gasoline by vacuum causes the gasoline undergoing vaporization to cool, thus interferring with the degree of vaporization attained with a given vacuum. Likewise, on compressing the vaporized light ends in the condenser the condensate and vapors increase in temperature due to heat released on condensation. This interferes with the condensation and requires higher condensing pressures. The modifications shown in FIGS. 4-6 tend to cancel out these effects.

In FIG. 4, gasoline tank 40 is connected to the fuel inlet of the engine carburetor (not shown) by liquid fuel conduit 41 in the same manner as in FIG. 3. Second liquid fuel conduit 42 connects gasoline tank 40 with vaporizing chamber 43 through one-way pressure regulating valve 44. In making this connection, second liquid fuel conduit 42 utilizes a portion of liquid fuel conduit 41 because the gasoline tank 40 is normally located at the rear of the vehicle whereas the vaporizing chamber 43 is normally located in the engine compartment at the front of the vehicle. Since both the liquid fuel conduit and the second liquid fuel conduit function to supply normal gasoline, it is more practical to utilize a common conduit from the rear gasoline tank up to the engine compartment.

Vapor conduit 45 connects vaporizing chamber 43 through its upper end closure to the inlet of compressor 46. The outlet of compressor 46 connects to condenser 47 which is a conduit helically coiled around the outside of the cylindrical side wall of vaporizing chamber 43 and is in contact with this side wall. FIG. 4 shows only three turns of condenser conduit 47 around vaporizer 43, but there can be as many turns as are required to obtain the required heat exchange from the condenser 47 to the vaporizer 43.

From condenser 47 condensate conduit 48 connects to volatile fuel tank 49 through one-way check valve A. Vapor conduit 41A connects the top of volatile fuel tank 49 to gas tank 40 through pressure relief valve 42A.

Vaporizing chamber 43 is connected through its bottom closure to pump 43A which in turn connects by volatile-depleted fuel conduit 44A through one-way check valve 45A to gas tank 40.

The embodiment shown in FIG. 4 operates in the same manner as that shown in FIG. 3. Pumps 46 and 43A are actuated by liquid level sensors as in FIG. 3. Efficiency of the vaporizer-condenser system is improved by the heat exchange coupling of the two functions.

In the embodiment of FIG. 5 the vaporizing chamber is placed inside the normal gasoline tank such that the normal gasoline is in contact with the side wall and bottom closure defining the vaporizing chamber. Gasoline tank 50 is connected in the normal manner to the carburetor fuel inlet by fuel conduit 51. Second fuel conduit 52 connects gas tank 50 through pressure regulating valve 53 to vaporizing chamber 54 through its top end closure. Vapor conduit 55 connects the top of chamber 54 to the inlet of compressor 56. The outlet of compressor 56 connects by conduit 57 through the wall of gasoline tank 50 to the condensing coils 58 located in the space within gasoline tank 50 and outside vaporizing chamber 54. Condenser coils 58 then connect by condensate conduit 59 through the wall of gasoline tank 50 to the volatile fuel tank in the manner shown in FIGS. 3 and 4.

Through the bottom end closure of chamber 54 volatile-depleted conduit 50A connects to the inlet of pump 51A. The outlet of pump 51A connects through oneway check valve 52A to gasoline tank 50. As shown, pump 51A and valve 52A are outside gasoline tank 50, which necessitates conduit 50A passing through the wall of gasoline tank 50 to reach pump 51A. Pump 5 1A can be a sealed unit placed within tank 50.

The embodiment shown in FIG. 5 operates in the same manner as that in FIG. 3. Pumps 56 and 51A are actuated by liquid level sensors in the volatile fuel tank and vaporizing chamber, respectively, as explained previously.

FIG. 6 shows another embodiment of the volatile fuel self-generation system. Gasoline tank 60-is connected in the normal manner to the fuel inlet of the engine carburetor (not shown) by fuel conduit 61. Second fuel conduit 62 connects gasoline tank 60 to vaporizing chamber 63 passing through pressure regulating valve 64. Vapor conduit 65 connects the top portion of vaporizing chamber 63 to the inlet of compressor 66. The outlet of compressor 66 connects by conduit 67 through the side wall of vaporizing chamber 63 to condensing conduit 68 coiled inside vaporizing chamber 63. Condensing conduit 68 connects by condensate conduit 69 out through the said wall of chamber 63 to the volatile fuel tank in the same manner as shown in FIGS. 3 and 4.

vaporizing chamber 63 connects through its bottom end closure by volatile-depleted conduit 63A to pump 64A which then connects by conduit 65A to gasoline tank 60. One-way check valve 66A is located in conduit 65A.

Operation of the embodiment of FIG. 6 is the same as that of FIG. 3. Liquid level sensing means (not shown) in the volatile fuel tank signal compressor 66 to operate when the liquid level in the volatile tank drops below a predetermined level. Compressor 66 evacuates chamber 63 causing pressure regulating valve 64 to admit normal gasoline into vaporizing chamber 63. The volatile portion of the gasoline is vaporized and the vapors compressed into condensing coils 68 where they form condensate and evolve heat which serves to help vaporize the normal gasoline admitted to the vaporizing chamber. The condensate is forced into the volatile fuel tank. Any uncondensables that build up in the volatile fuel tank are returned to gasoline tank 60 through a pressure relief valve as shown in FIGS. 3 and 4.

A rise in the liquid level in vaporizing chamber 63 causes a liquid level sensor (not shown) to signal pump 64A to operate by pumping the volatile-depleted fuel back to gasoline tank 60 through conduit 65A and oneway check valve 66A.

Both normal gasoline and volatile gasoline are delivered to the engine carburetor through fuel switching means that deliver volatile fuel on start and warm-up and normal gasoline after the engine attains an adequate operating temperature as described in the embodiment of FIG. 3.

In the embodiment shown in FIG. 7 a supplemental heat source is used to vaporize the gasoline. In FIG. 7, gas tank 70 connects by fuel conduit 71 to the fuel inlet of the engine carburetor (not shown). A second fuel conduit 72 connects gasoline tank 70 through pressure regulating valve 73 to vaporizing chamber 74. Vaporizing chamber 74 is formed by substantially cylindrical wall 75 and end closures 76 and 77. The vaporizing chamber is jacketed by providing an outer substantially cylindrical wall 78 and end closures 79 and 70A which form a closed annular space 71A between side wall 75 and outer wall 78. Liquid coolant is conducted by standard means from the engine and enters annular space 71A through inlet 72A in outer wall 78 wherein it circulates. The liquid coolant leaves annular space 71A through exit 73A from where it is conducted back to the engine cooling system.

Vapor conduit 74A connects the top of vaporizing chamber 74 through end closure 76 to compressor 75A. The outlet of compressor 75A connects to finned tube condenser 76A. The outlet of finned tube condenser 76A connects through one-way check valve 77A to volatile fuel tank 78A. The bottom of tank 78A connects by volatile fuel conduit 79A to the inlet of the engine carburetor (not shown) in the manner described in FIG. 3. The top of fuel tank 78A connects through pressure relief valve 708 and vent conduit 71B to gasoline tank 70.

Vaporizing chamber 74 connects through bottom end closure 77 by volatile-depleted conduit 72B to pump 73B. The outlet of pump 73B connects by conduit 748 through one-way check valve 755 to gasoline tank 70.

The embodiment of FIG. 7 operates in substantially the same manner as that of FIG. 3. It differs in the addition of supplemental heat to the vaporizing chamber by the engine coolant. Since the system operates most efficiently after the engine liquid is hot, it is preferred to include in this embodiment a thermo switch responsive to engine coolant temperature that prevents operation of pump A until the engine coolant is heated to a temperature adequate to vaporize the light ends of the normal gasoline. Since the initial boiling point of normal gasoline is about 80F, it is generally satisfactory to set the thermo switch to permit pump 75A to operate when the coolant reaches a temperature of about 130F.

In another embodiment of the invention hot exhaust gas is used to supply the supplemental heat to the vaporizing chamber of the engine coolant. In this embodiment an exhaust shunt is provided in the exhaust system which diverts hot exhaust gas to the vaporizing chamber whenever the liquid level sensor in the volatile fuel tank 78A is actuated by a low liquid level to signal operation of pump 75A.

In further embodiments, the heat used to vaporize the light-end of the gasoline delivered to vaporizing chamber 74 is supplied by other vehicle heat sources such as the crankcase lubricant, transmission fluid, and the like.

In general, it is preferred to maintain the volatile liquid fuel in the vapor liquid fuel tank under moderate pressure to avoid loss by evaporation. A pressure range of from about 5 to 75 psig is generally adequate for this purpose. However, under conditions in which the volatile fuel tank is exposed to high temperatures such as those in the engine compartment, higher pressure may be desirable. When the volatile liquid fuel is maintained under pressure it is preferred to include in the volatile liquid fuel conduit a pressure reduction valve such that the pressure of the volatile liquid fuel delivered to the inlet of the carburetor fuel bowl is low enough so that it can be readily metered into the fuel how] by a fuel bowl float actuated valve.

The embodiment in FIG. 8 includes a gasoline tank 80 connected by fuel conduit 81 through valve 82, pump 83 and valve 84 to the fuel inlet of fuel bowl of a liquid fuel carburetor. Second fuel conduit 86 connects through pressure regulating valve 87 to vaporizer 88 formed by a circular side wall and end closures. As shown, the bottom end closure is in the form of an inverted cone. The top end closure may also be conical in order to better withstand the vacuum which is generally maintained within the vaporizer. Vaporizer 88 connects by volatile fuel conduit 89 through its top end closure to pump 80A, which in turn connects to condensing tube 81A coiled within vaporizer 88. Condensing tube 81A connects through condensate conduit 82A and pressure regulating valve 83A to volatile fuel tank 84A, which is spherical to withstand substantial internal pressure. Inside tank 84A is liquid level actuated switch 85A which is electrically connected to pump 80A. The top of tank 84A connects through vapor conduit 86A and pressure relief valve 87A to gasoline tank 80. The bottom of tank 84A connects through volatile fuel conduit 88A, pressure regulating valve 89A and valve 80B to the fuel inlet of fuel bowl 85. FIG. 8 does not show the fuel bowl drain as shown in FIGS. 1 and 3, but this feature is preferably included.

In operation starting with a cold engine'both valve 84 and 80B are closed. When the ignition is turned on, valve 808 opens in response to temperature sensors installed in the engine and fuel bowl 85 fills with volatile fuel delivered from tank 84A through conduit 88A and pressure regulating valve 89A. Valve 89A reduces the pressure from that in volatile-fuel storage tank 84A (approximately, 75 psig) to a pressure that can be controlled by the float actuated valve in fuel bowl 85. This reduced pressure is generally about 1-5 psig.

The engine starts readily on the volatile fuel without any choking and warms toward normal operating temperature. When the engine temperature sensors reach a temperature at which experience has shown the engine will operate satisfactorily on normal gasoline without choking, they signal valve 84 to open and valve 808 to close. Normal engine operation continues using gasoline.

The resultant reduction in the liquid level in tank 84A is detected by liquid level switch 85A which starts pump 80A. Pump 80A may be electrically driven or may be belt driven by the engine. Pump 80A functions to remove fuel vapor from vaporizer 88 and compresses it into condensing tube 81A wherein it is cooled and condensed to form volatile fuel condensate. When the pressure in condensing tube 81A reaches a predetermined level which is above the pressure in tank 84A and adequate to cause the fuel vapor to condense, pressure regulator valve 83A allows a controlled amount of the condensate to pass through conduit 82A into tank 84A, thus replenishing the supply of volatile fuel. Alternatively, valve 83A may be a one-way check valve which passes condensate into tank 84A as soon as its pressure exceeds that in tank 84A.

As a result of pump 80A, the pressure in vaporizer 88 drops, and at a predetermined level between about l-l4 psig, pressure regulator valve 87 opens and meters gasoline from gasoline tank 80 through second fuel conduit 86 into 1 vaporizer 88 at a rate adequate to maintain the predetermined vacuum in vaporizer 88 at a substantially constant level. A spray nozzle can be attached at the outlet of conduit 86 inside vaporizer 88.

When the gasoline enters vaporizer 88 it is partially vaporized furnishing additional vapors to pump 80A. The volatile-depleted fuel drops to the bottom of vaporizer 88 where it serves to cool condenser tube 81A. If desired, additional heat can be supplied to vaporizer 88 to assist vaporization by such means as electrical heaters or, preferably, by a jacket through which hot coolant or exhaust from the engine is passed.

The amount of volatiles removed from the gasoline to form volatile condensate depends to a large extent on the composition of the fuel. Fortunately, in cold months when a larger amount of volatile condensate will be required, there is a greater proportion of such volatile components (e.g., butanes, pentanes, hexanes) in the gasoline. The degree to which the gasoline is stripped of volatiles is best determined experimentally. A useful guide is to remove a volatile fraction having a boiling range (ASTM D-86) up to about 300F., more preferably up to about 150F. Individual components of the condensate, for example, butanes and pentanes, may individually boil from about -l0F. (isobutane) to about 96"-F. (n-pentane). These low boiling components are very effective in eliminating the need for choking the engine.

The volatile-depleted fuel collects at the bottom of vaporizer 88. In a highly preferred embodiment this volatile-depleted fuel is not returned to gasoline tank but is instead stored in a volatile-depleted fuel tank 818, and when available, is used to operate the engine whenever it is at normal operating temperature. When the engine is at its normal operating temperature it can operate efficiently on such volatile-depleted fuel without any substantial increase in exhaust hydrocarbon or carbon monoxide emission. In this manner, the accumulation of volatile-depleted fuel in gas tank 80 is avoided, thus assuring that the gasoline will contain a sufficient amount of volatile components to allow efficient operation of the vaporizer. The fuel system of the present invention will operate effectively without this improved feature but generally will provide volatile condensate for about 20-50 cold starts per each 20 gallon tank of gasoline before the volatile level in the gasoline becomes too low to permit efficient operation of the vaporizer.

Pump 82B is started when the liquid level in vaporizer 88 attains a predetermined level, which level still permits efficient operation of the vaporizer. This level is readily detected by a liquid level actuated switch (not shown) which starts pump 82B. Pump 82B pumps the volatile-depleted fuel through conduit 83B and oneway check valve 848 into tank 818. This tank may be vented since the fuel stored therein has been stripped of its volatile components. Liquid level switch 85B functions to keep valves 868 open and 82 closed when there is volatile-depleted fuel available in tank 81B to operate the engine. As a safety item, switch 85B, when it senses that tank 813 is full to capacity, will open I both valves 86B and 82 allowing volatile-depleted fuel to drain back'to gas tank 80 until a safe level is attained in tank 818, at which time switch 858 closes valve 82.

When the liquid level in tank 818 drops to about empty, switch 85B closes valve 86B and opens valve 82 allowing the engine to operate on gasoline from gas tank 80.

As a further embodiment, valves 86B and 82 can function such that, rather than completely closing valve 82 when volatile-depleted fuel is available in tank 818, it is only partially closed, thus mixing gasoline from tank 80 with the volatile-depleted fuel from tank 818 in a ratio that gives improved engine operation.

FIG. 9 shows another embodiment of the invention in which a highly volatile condensate is removed from gasoline and used as the fuel source for a gaseous fuel metering system. In other words, in this embodiment there are two fuel metering systems one metering liquid fuel and the other metering gaseous fuel. When it is stated herein that a particular embodiment has a or may be multiple venturi such as a 2, 3 or 4 venturi carburetor. Also, more than one carburetor may be used on a single engine to gain improved volumetric efticiency. The common feature is that in all these embodiments only a liquid fuel metering system is employed. In the embodiment now to be described two fuel metering systems are employed one a liquid fuel metering system (e.g., fuel injector, carburetor) and the other a gaseous fuel metering system of the type commonly used in LPG fueled engines.

The embodiment shown in FIG. 9 comprises gasoline tank 90 connected by fuel conduit 91 through valve 92 and fuel pump 93 to fuel bowl 94 of carburetor 95 mounted on the intake manifold of an internal combustion engine. Valve 95B is the passage between the fuel jet and nozzle. Tank 90 connects through conduit 96 and pressure regulating valve 97 to first vaporizer 98. Vaporizer 98 connects through vapor conduit 99 and pump 90A to condensing tube 91A. Vaporizer 98 is jacketed by housing 91B which provides a plenum space 9213 between the vaporizer housing and the jacket housing. Jacket housing 918 has an entry port 938 and exit port 94B to the plenum space 928.

Condensing tube 91A connects through condensate conduit 95B and pressure regulating valve 96B to volatile fuel tank 973. The top of volatile fuel tank 97B is vented through pressure relief valve 988 and vapor conduit 998 to the bottom area of gasoline tank 90. Located within tank 978 is liquid level actuated switch 90C.

The bottom of tank 97B connects through conduit 91C and first pressure reducing valve 92C to second vaporizer 93C which is formed by housing 94C. Outer housing 95C provides a heating jacket for the second vaporizer 93C which has an inlet 96C and outlet 97C for a heating material. Vaporizer 93C also has a drain conduit 98C through valve 99C.

The top of second vaporizer 93C connects through second pressure reduction valve 90D and conduit 91D to a standard gaseous fuel/air metering device 92D. Air enters metering device 92D through air inlet 93D and the gaseous fuel/air mixture is conducted to the air intake 93E of carburetor 95.

The bottom of first vaporizer 98 connects through pump 96D, volatile-depleted fuel conduit 97D and oneway check valve 98D to volatile-depleted fuel tank 99D. Within tank 99D is liquid level actuated switch 905. The bottom of tank 99D connects through valve 91E and fuel pump 93 to fuel bowl 94 of carburetor 95 mounted on the intake manifold of an internal combustion engine.

FIG. 10 is a cross-section of a typical air/vapor fuel metering and mixing device. It comprises fuel vapor conduit 100 which connects to mixing zone 101 through circular orifice 102. Air enters inlet 103 and enters mixing zone 101 at circular orifice 104. Valve member 105 is attached to diaphragm 106 and can move up and down and seats on circular orifices 102 and 104. Spring 107 presses valve member 105 against orifices 102 and 104. When throttle valve 92E opens and valve 94E is closed pressure drops in mixing zone 101. The pressure drop is equalized to actuating chamber 108 by ports 109 in valve member 105. Since the effective area in chamber 108 is greater than the area between orifices 102 and 104, valve member 105 lifts, allowing air and fuel vapor to enter the mixing zone. The ratio of air to fuel is controlled by the relative size of orifices 102 and 104 and by the vapor pressure in conduit 100 which is regulated by valve 90D, generally at slightly below atmospheric pressure.

In operation starting with a cold engine, thermoswitches mounted on the engine sense the low temperature condition and function to close valve 94E and 95E and to open valve 95D. Cranking the engine reduces pressure in conduit 94D and inducts a mixture of gaseous fuel and air from metering device 92D. Second regulating valve D opens to meet demand and permits fuel vapor from tank 93C to enter metering device 92D. In practice, the fuel vapor pressure in conduit 91D is maintained slightly below atmospheric in case an accidental leak downstream of regulating valve 90D. When pressure in second vaporizer 93C starts to drop, liquid volatile fuel from tank 97B is admitted to vaporizer 93C through first pressure regulating valve 92C. This valve is adjusted to maintain a satisfactory amount of fuel in second vaporizer 93C in the gaseous form at ambient temperatures to at least start the engine. A useful pressure range in second vaporizer 93C is from about 1l5 psig. In extreme cold conditions vaporizer 93C can be pre-heated electrically to provide enough vapor to start the engine but this is not usually required. Once the engine starts, vaporizer 93C can be heated by passing hot exhaust gas through the heating jacket formed by housing 95C or, alternatively, by engine coolant.

As additional volatile liquid fuel is supplied to second vaporizer 93C from tank 97B, the liquid level in tank 97E drops. At a predetermined level, switch 90C signals pump 90A to start operating. Pump 90A pumps fuel vapor from first vaporizer 98 and compresses it in condenser tube 91A wherein it cools and condenses and is forced through regulating valve 963 into tank 97B. Alternatively, valve 96B can be a one-way check valve. As vapor is pumped from first vaporizer 98, the pressure therein drops and gasoline from tank 90 is drawn in by vacuum at a metered rate through conduit 96 and regulating valve 97. Regulating valve 97 is set to maintain enough vacuum in vaporizer 98 to vaporize the light ends of the gasoline. In this embodiment, only the most volatile components are removed from gasoline such as the propane, butanes and pentanes. Pressure within vaporizer 98 can be maintained from about 1-14 psia, preferably from about lO-l4 psia, to accomplish this depending on the temperature in the vaporizer. 1n the preferred embodiment shown the temperature within the vaporizer is maintained at an elevated level by circulating thermostatically controlled coolant through jacket 92B. Additionally, the amount of coolant may be varied to provide a constant temperature (e.g., IOO-ISOF.) in the volatile-depleted fuel that collects at the bottom of vaporizer 98. By controlling vacuum and temperature in the first vaporizer, a narrow range of volatiles can be removed. Since these volatiles are again to be vaporized after condensation, it is preferable to minimize the amount of higher boiling material carried with them since this material is more difficult to vaporize in second vaporizer 93C. As an aid in this some distillation packing can be provided in conduit 99 upstream from pump 90A. Alternatively, some standard distillation structure can be incorportated in conduit 99 such as a number of bubble cap plates.

In this embodiment a useful range of volatiles removed from the gasoline and condensed as a source of volatile fuel are those boiling up to about 150F. and, more preferably, up to about F. (ASTM D-86).

The volatile-depleted fuel that collects in the bottom of first vaporizer 98 is pumped by pump 96D to tank 99D and used preferentially at normal operating temperature in the same manner as in the FIG. 8 embodi ment.

liquid fuel to the engine through conduit 91, valve 92,,

and fuel pump 93. As in the FIG. 8 embodiment, once the engine attains -full operating temperature, valve 91B is signaled to open if liquid level switch 90E indicates adequate volatiledepleted fuel. Valve 92 may be fully or partially closed at this time to assure preferential use of the volatile-depleted fuel while the engine is hot.

1 By the practice of the above-described invention, the exhaust hydrocarbon and carbon monoxide emission is substantially reduced. This reduction is obtained while supplying the vehicle with normal gasoline without the necessity of supplying two separate fuels to the vehicle.

We claim:

l. A fuel system for a spark ignited internal combustion engine having carburetor fuel induction 'means, said fuel system comprising:

a. a container for liquid hydrocarbon fuel of the gasoline boiling range connected by a liquid fuel conduit to the fuel inlet of said carburetor,

b. a container for liquid hydrocarbon fuel of the lower gasoline boiling range connected by a volatile liquid fuel conduit to said fuel inlet of said carburetor, v

c. valve means in said liquid fuel conduit and volatile liquid fuel conduit adapted to:

1. close said liquid fuel conduit and open said volatile liquid fuel conduit during start and warm-up of said engine, and

2. open said liquid fuel conduit and close said volatile liquid fuel conduit after warm-up of said engine and d. a vapor conduit connecting the top of said container for liquid hydrocarbon fuel of the lower gasoline boiling range to the normally liquid containing zone of said container for liquid hydrocarbon fuel of the gasoline boiling range, said vapor conduit having one-way pressure relief valve means adaptedto permit vapor to flow to said normally liquid containing zone whenever the pressure in said container for liquid'hydrocarbon fuel of the lower gasoline boiling range rises above a predetermined pressure.

2. A fuel system of claim 1, said system including engine temperature sensing means and-valve actuating means, said temperature sensing means being responsive to the engine temperature such that whensaid temperature is below a predetermined operating temperature said temperature sensing means signals said valve actuating means to close said valve means in said liquid fuel conduit and open said valve means in said volatile liquid fuel conduit, and such that when said temperature rises to said operating temperature said temperature sensing means signals said valve actuating means to open said valve means in said liquid fuel conduit and close said valve means in said volatile liquid fuel conduit.

3. A fuel system of claim 1 wherein said container for liquid hydrocarbon fuels of the gasoline boiling range is connected by a second liquid fuel conduit to fuel vaporizing means adapted to vaporize the light ends from said liquid hydrocarbon fuel of the gasoline boiling range forming vaporized light ends and volatiledepleted fuel, said vaporizing means being connected by a vapor conduit to condensing means whereby said vaporized light ends are condensed to form volatile fuel condensates, said condensing means being connected by a volatile fuel condensate conduit to said container for liquid hydrocarbon fuels of the lower gasoline boiling range adapted to conduct said volatile fuel condensate to said container for liquid hydrocarbon fuels of the lower gasoline boiling range, said vaporizing means being connected by a volatile-depleted fuel conduit to said container for liquid hydrocarbon fuels of the gasoline boiling range adapted to conduct said volatiledepleted fuel to said container for liquid hydrocarbon fuel of the gasoline boiling range.

4. A fuel system of claim 3, said system including engine temperature sensing means and valve actuating means, said temperature sensing means being responsive to the engine temperature such that'when said temperature is below a predetermined operating temperature said temperature sensing means signals said valve actuating means to close said valve means in said liquid fuel conduit and open said valve'mean's in said volatile liquid fuel conduit, andsucli that when said temperature rises to said operating temperature said temperature sensing means signals said valve actuating means toopen said valve means in said liquid fuel conduit and close said valve means in said volatile liquid fuel conduit. I

5. A fuel system of claim 4, having vapor pump means in said vapor conduit adapted to pump said vaporized light ends to said condensing means and volatile-depleted pump means in said volatile-depleted fuel conduit adapted to pump said volatile-depleted fuel back to said container for liquid hydrocarbon fuel of the gasoline boiling range.

6. A fuel system of claim 5, having one-way valve means in said volatile fuel condensate conduit adapted to permit said volatile fuel condensate to flow to said container for liquid hydrocarbon fuels of the lower gasoline boiling range and to prevent flow in the reverse direction. i v

7. A fuel system of claim 6, having one-way valve means in said volatile-depleted fuel conduit adapted to permit said volatile-depleted fuel to flow to said container for liquid hydrocarbon fuel of the gasoline boiling range and to prevent flow in the reverse direction.

8. A fuel system of claim 7, having one-way pressure relief valve means in said second liquid fuel conduit,

' said pressure relief valve means adapted to open whenever the pressure on said fuel vaporizing means side of said pressure relief valve is from about 3-10 psig lower than on the opposite side of said pressure relief valve.

operating temperature.

10. A fuel system of claim 9, having volatile-depleted liquid level sensing means responsive to the volatiledepleted liquid level in said vaporizing means, said volatile-depleted liquid level sensing means functioning to signal said volatile-depleted pump means in said volatile-depleted fuel conduit to operate whenever said volatile-depleted liquid level rises above a predetermined level.

ll. A fuel system of claim 1 having carburetor drain means adapted to drain residual fuel from said carburetor to the storage container for said liquid hydrocarbon fuel of the gasoline boiling range when said engine is stopped and having carburetor drain valve means in said carburetor drain means said carburetor drain valve means being responsive to the electrical ignition system of said engine such that when said ignition system is turned on said carburetor drain valve means close, and when said electrical ignition system is turned off said carburetor valve means open.

12. A fuel system of claim 5 comprising fuel vaporizing means adapted to vaporize the light ends from said liquid hydrocarbon fuel of the gasoline boiling range forming vaporized light ends and volatile-depleted fuel, and condensing means whereby said vaporized light ends are condensed to form said liquid hydrocarbon fuel of the lower gasoline boiling range.

13. A fuel system for a spark ignited internal combustion engine having carburetor fuel induction means, said fuel system comprising:

a. a container for liquid hydrocarbon fuel of the gasoline boiling range connected by a liquid fuel conduit to the fuel inlet of said carburetor,

b. fuel vaporizing means adapted to vaporize the light ends from said liquid hydrocarbon fuel of the gasoline boiling range forming vaporized light ends and volatile-depleted fuel, said fuel vaporizing means being connected to said container for liquid hydrocarbon fuel of the gasoline boiling range by a second liquid fuel conduit,

c. a container for volatile fuel condensate connected by a volatile fuel conduit to said fuel inlet of said carburetor,

d. condensing means connected by a vapor conduit to said fuel vaporizing means and by a volatile fuel condensate conduit to said container for volatile fuel condensate, said condensing means being adapted to condense said vaporized light ends to form said volatile fuel condensate,

. vapor pump means in said vapor conduit adapted to pump said vaporized light ends to said condensing means,

f. a one-way check valve in the conduit from said fuel vaporizing means to said container for volatile fuel condensate between said vapor pump means and said container for volatile fuel condensate adapted to permit flow to said container for volatile fuel condensate and to prevent flow in the reverse direction,

g. valve means in said liquid fuel conduit and said volatile fuel conduit adapted to:

1. close said liquid fuel conduit and open said volatile liquid fuel conduit during start and warm-up of said engine, and

2. open said liquid fuel conduit and close said volatile liquid fuel conduit after warm-up of said en- 20 gine, and

h. a second vapor conduit connecting the top of said container for volatile fuel condensate to the lower normally liquid containing zone of said container for liquid hydrocarbon fuel of the gasoline boiling range, said second vapor conduit having one-way pressure relief valve means adapted to permit vapor to flow to'said normally liquid containing zone whenever the pressure in said container for volatile fuel condensate rises above a predetermined pressure.

14. A fuel system of claim 13. having a volatiledepleted fuel conduit connecting said vaporizing means to said container for liquid hydrocarbon fuel of the gasoline boiling range adapted to conduct said volatiledepleted fuel to said container for liquid hydrocarbon fuel of the gasoline boiling range and one-way valve means in said volatile-depleted fuel conduit adapted to permit said volatile-depleted fuel to flow to said container for liquid hydrocarbon fuel of the gasoline boiling range and to prevent flow in the reverse direction.

15. A fuel system of claim 13 having a one-way pressure relief valve in said second liquid fuel conduit, said pressure relief valve adapted to open whenever the pressure on said fuel vaporizing means side of said pressure relief valve is from about 3-10 psig lower than on .the opposite side of said pressure relief valve.

17. A fuel system of claim 16, having a volatiledepleted fuel conduit connecting said vaporizing means to said container for liquid hydrocarbon fuel of the gasoline boiling range, volatile-depleted pump means in said volatile-depleted fuel conduit adapted to pump said volatile-depleted fuel to said container for liquid hydrocarbon fuel of the gasoline boiling range and volatile-depleted liquid level sensing means responsive to the volatile-depleted'liquid level in said vaporizing means, said volatile-depleted liquid level sensing means functioning to signal said volatile-depleted pump means in said volatile-depleted fuel to operate whenever said volatile-depleted liquid level rises above a predetermined level.

18. A fuel system of claim 16, having carburetor drain means adapted to drain residual fuel from the bowl of said carburetor to said container for liquid hydrocarbon fuel of the gasoline boiling range when said engine is stopped and having carburetor drain valve means in said carburetor drain means, said carburetor drain valve means being responsive to the electrical ignition system of said engine such that when said ignition system is turned on said carburetor drain valve means close and when said electrical ignition system is turned off said carburetor valve means open.

mg UNITED STATES PATENT @FFIICIE CERTIFICATE OF @ORREQTIGN Patent No. 5, 7,577 Dated April 50, 197A Inventor) Daniel A. Hirschler, Jr. and Frederick J. Marsee It is certified that errot appears in the abcve-identified patent and that said Letters Patent are hereby correeted as shown below:

Column 19, Claim 12, line 1, "Claim 5" should read Claim 1 Signed and sealed this 10th day of September 1974 (SEAL) Attest:

MCCOY M. GIBSON, JR. C, MARSHALL DANN Attest'ing Officer Commissioner of Patents 

1. A fuel system for a spark ignited internal combustion engine having carburetor fuel induction means, said fuel system comprising: a. a container for liquid hydrocarbon fuel of the gasoline boiling range connected by a liquid fuel conduit to the fuel inlet of said carburetor, b. a container for liquid hydrocarbon fuel of the lower gasoline boiling range connected by a volatile liquid fuel conduit to said fuel inlet of said carburetor, c. valve means in said liquid fuel conduit and volatile liquid fuel conduit adapted to:
 1. close said liquid fuel conduit and open said volatile liquid fuel conduit during start and warm-up of said engine, and
 2. open said liquid fuel conduit and close said volatile liquid fuel conduit after warm-up of said engine and d. a vapor conduit connecting the top of said container for liquid hydrocarbon fuel of the lower gasoline boiling range to the normally liquid containing zone of said container for liquid hydrocarbon fuel of the gasoline boiling range, said vapor conduit having one-way pressure relief valve means adapted to permit vapor to flow to said normally liquid containing zone whenever the pressure in said container for liquid hydrocarbon fuel of the lower gasoline boiling range rises above a predetermined pressure.
 2. A fuel system of claim 1, said system including engine temperature sensing means and valve actuating means, said temperature sensing means being responsive to the engine temperature such that when said temperature is below a predetermined operating temperature said temperature sensing means signals said valve actuating means to close said valve means in said liquid fuel conduit and open said valve means in said volatile liquid fuel conduit, and such that when said temperature rises to said operating temperature said temperature sensing means signals said valve actuating means to open said valve means in said liquid fuel conduit and close said valve means in said volatile liquid fuel conduit.
 2. open said liquid fuel conduit and close said volatile liquid fuel conduit after warm-up of said engine and d. a vapor conduit connecting the top of said container for liquid hydrocarbon fuel of the lower gasoline boiling range to the normally liquid containing zone of said container for liquid hydrocarbon fuel of the gasoline boiling range, said vapor conduit having one-way pressure relief valve means adapted to permit vapor to flow to said normally liquid containing zone whenever the pressure in said container for liquid hydrocarbon fuel of the lower gasoline boiling range rises above a predetermined pressure.
 2. open said liquid fuel conduit and close said volatile liquid fuel conduit after warm-up of said engine, and h. a second vapor conduit connecting the top of said container for volatile fuel condensate to the lower normally liquid containing zone of said container for liquid hydrocarbon fuel of the gasoline boiling range, said second vapor conduit having one-way pressure relief valve means adapted to permit vapor to flow to said normally liquid containing zone whenever the pressure in said container for volatile fuel condensate rises above a predetermined pressure.
 3. A fuel system of claim 1 wherein said container for liquid hydrocarbon fuels of the gasoline boiling range is connected by a second liquid fuel conduit to fuel vaporizing means adapted to vaporize the light ends from said liquid hydrocarbon fuel of the gasoline boiling range forming vaporized light ends and volatile-depleted fuel, said vaporizing means being Connected by a vapor conduit to condensing means whereby said vaporized light ends are condensed to form volatile fuel condensates, said condensing means being connected by a volatile fuel condensate conduit to said container for liquid hydrocarbon fuels of the lower gasoline boiling range adapted to conduct said volatile fuel condensate to said container for liquid hydrocarbon fuels of the lower gasoline boiling range, said vaporizing means being connected by a volatile-depleted fuel conduit to said container for liquid hydrocarbon fuels of the gasoline boiling range adapted to conduct said volatile-depleted fuel to said container for liquid hydrocarbon fuel of the gasoline boiling range.
 4. A fuel system of claim 3, said system including engine temperature sensing means and valve actuating means, said temperature sensing means being responsive to the engine temperature such that when said temperature is below a predetermined operating temperature said temperature sensing means signals said valve actuating means to close said valve means in said liquid fuel conduit and open said valve means in said volatile liquid fuel conduit, and such that when said temperature rises to said operating temperature said temperature sensing means signals said valve actuating means to open said valve means in said liquid fuel conduit and close said valve means in said volatile liquid fuel conduit.
 5. A fuel system of claim 4, having vapor pump means in said vapor conduit adapted to pump said vaporized light ends to said condensing means and volatile-depleted pump means in said volatile-depleted fuel conduit adapted to pump said volatile-depleted fuel back to said container for liquid hydrocarbon fuel of the gasoline boiling range.
 6. A fuel system of claim 5, having one-way valve means in said volatile fuel condensate conduit adapted to permit said volatile fuel condensate to flow to said container for liquid hydrocarbon fuels of the lower gasoline boiling range and to prevent flow in the reverse direction.
 7. A fuel system of claim 6, having one-way valve means in said volatile-depleted fuel conduit adapted to permit said volatile-depleted fuel to flow to said container for liquid hydrocarbon fuel of the gasoline boiling range and to prevent flow in the reverse direction.
 8. A fuel system of claim 7, having one-way pressure relief valve means in said second liquid fuel conduit, said pressure relief valve means adapted to open whenever the pressure on said fuel vaporizing means side of said pressure relief valve is from about 3-10 psig lower than on the opposite side of said pressure relief valve.
 9. A fuel system of claim 8 having liquid level sensing means responsive to the liquid level in said container for liquid hydrocarbon fuel of the lower gasoline boiling range, said liquid level sensing means functioning to signal said vapor pump means to operate whenever said liquid level drops below a predetermined level, said predetermined level being at least sufficient to provide enough liquid hydrocarbon fuel of the lower gasoline boiling range to start and operate said engine for a period of time sufficient to bring its temperature to said operating temperature.
 10. A fuel system of claim 9, having volatile-depleted liquid level sensing means responsive to the volatile-depleted liquid level in said vaporizing means, said volatile-depleted liquid level sensing means functioning to signal said volatile-depleted pump means in said volatile-depleted fuel conduit to operate whenever said volatile-depleted liquid level rises above a predetermined level.
 11. A fuel system of claim 1 having carburetor drain means adapted to drain residual fuel from said carburetor to the storage container for said liquid hydrocarbon fuel of the gasoline boiling range when said engine is stopped and having carburetor drain valve means in said carburetor drain means said carburetor drain valve means being responsive to the electrical ignition system of said engine such that when said ignItion system is turned on said carburetor drain valve means close, and when said electrical ignition system is turned off said carburetor valve means open.
 12. A fuel system of claim 5 comprising fuel vaporizing means adapted to vaporize the light ends from said liquid hydrocarbon fuel of the gasoline boiling range forming vaporized light ends and volatile-depleted fuel, and condensing means whereby said vaporized light ends are condensed to form said liquid hydrocarbon fuel of the lower gasoline boiling range.
 13. A fuel system for a spark ignited internal combustion engine having carburetor fuel induction means, said fuel system comprising: a. a container for liquid hydrocarbon fuel of the gasoline boiling range connected by a liquid fuel conduit to the fuel inlet of said carburetor, b. fuel vaporizing means adapted to vaporize the light ends from said liquid hydrocarbon fuel of the gasoline boiling range forming vaporized light ends and volatile-depleted fuel, said fuel vaporizing means being connected to said container for liquid hydrocarbon fuel of the gasoline boiling range by a second liquid fuel conduit, c. a container for volatile fuel condensate connected by a volatile fuel conduit to said fuel inlet of said carburetor, d. condensing means connected by a vapor conduit to said fuel vaporizing means and by a volatile fuel condensate conduit to said container for volatile fuel condensate, said condensing means being adapted to condense said vaporized light ends to form said volatile fuel condensate, e. vapor pump means in said vapor conduit adapted to pump said vaporized light ends to said condensing means, f. a one-way check valve in the conduit from said fuel vaporizing means to said container for volatile fuel condensate between said vapor pump means and said container for volatile fuel condensate adapted to permit flow to said container for volatile fuel condensate and to prevent flow in the reverse direction, g. valve means in said liquid fuel conduit and said volatile fuel conduit adapted to:
 14. A fuel system of claim
 13. having a volatile-depleted fuel conduit connecting said vaporizing means to said container for liquid hydrocarbon fuel of the gasoline boiling range adapted to conduct said volatile-depleted fuel to said container for liquid hydrocarbon fuel of the gasoline boiling range and one-way valve means in said volatile-depleted fuel conduit adapted to permit said volatile-depleted fuel to flow to said container for liquid hydrocarbon fuel of the gasoline boiling range and to prevent flow in the reverse direction.
 15. A fuel system of claim 13 having a one-way pressure relief valve in said second liquid fuel conduit, said pressure relief valve adapted to open whenever the pressure on said fuel vaporizing means side of said pressure relief valve is from about 3-10 psig lower than on the opposite side of said pressure relief valve.
 16. A fuel system of claim 13 including: i. liquid level sensing means responsive to the liquid level in said container for volatile fuel condensate, said liquid level sensing means functioning to signal said vapor pump means to operate whenever said liquid level drops below a predetermined level, said predetermined level being at least sufficient tO provide enough volatile fuel condensate to start and operate said engine for a period of time sufficient to raise its temperature to operating temperature.
 17. A fuel system of claim 16, having a volatile-depleted fuel conduit connecting said vaporizing means to said container for liquid hydrocarbon fuel of the gasoline boiling range, volatile-depleted pump means in said volatile-depleted fuel conduit adapted to pump said volatile-depleted fuel to said container for liquid hydrocarbon fuel of the gasoline boiling range and volatile-depleted liquid level sensing means responsive to the volatile-depleted liquid level in said vaporizing means, said volatile-depleted liquid level sensing means functioning to signal said volatile-depleted pump means in said volatile-depleted fuel to operate whenever said volatile-depleted liquid level rises above a predetermined level.
 18. A fuel system of claim 16, having carburetor drain means adapted to drain residual fuel from the bowl of said carburetor to said container for liquid hydrocarbon fuel of the gasoline boiling range when said engine is stopped and having carburetor drain valve means in said carburetor drain means, said carburetor drain valve means being responsive to the electrical ignition system of said engine such that when said ignition system is turned on said carburetor drain valve means close and when said electrical ignition system is turned off said carburetor valve means open. 